kotlin-stdlib/kotlin.collections/lastOrNull

lastOrNull

fun <T> Array<out T>.lastOrNull(): T?

fun ByteArray.lastOrNull(): Byte?

fun ShortArray.lastOrNull(): Short?

fun IntArray.lastOrNull(): Int?

fun LongArray.lastOrNull(): Long?

fun FloatArray.lastOrNull(): Float?

fun DoubleArray.lastOrNull(): Double?

fun BooleanArray.lastOrNull(): Boolean?

fun CharArray.lastOrNull(): Char?

Returns the last element, or null if the array is empty.

Samples

import samples.*
import kotlin.test.*
fun main() { 
   //sampleStart 
   val list = listOf(1, 2, 3, 4)
assertPrints(list.last(), "4")
assertPrints(list.last { it % 2 == 1 }, "3")
assertPrints(list.lastOrNull { it < 0 }, "null")
assertFails { list.last { it < 0 } }

val emptyList = emptyList<Int>()
assertPrints(emptyList.lastOrNull(), "null")
assertFails { emptyList.last() } 
   //sampleEnd
}

inline fun <T> Array<out T>.lastOrNull(predicate: (T) -> Boolean): T?

inline fun ByteArray.lastOrNull(predicate: (Byte) -> Boolean): Byte?

inline fun ShortArray.lastOrNull(predicate: (Short) -> Boolean): Short?

inline fun IntArray.lastOrNull(predicate: (Int) -> Boolean): Int?

inline fun LongArray.lastOrNull(predicate: (Long) -> Boolean): Long?

inline fun FloatArray.lastOrNull(predicate: (Float) -> Boolean): Float?

inline fun DoubleArray.lastOrNull(predicate: (Double) -> Boolean): Double?

inline fun BooleanArray.lastOrNull(predicate: (Boolean) -> Boolean): Boolean?

inline fun CharArray.lastOrNull(predicate: (Char) -> Boolean): Char?

inline fun <T> Iterable<T>.lastOrNull(predicate: (T) -> Boolean): T?

inline fun <T> List<T>.lastOrNull(predicate: (T) -> Boolean): T?

Returns the last element matching the given predicate, or null if no such element was found.

Samples

import samples.*
import kotlin.test.*
fun main() { 
   //sampleStart 
   val list = listOf(1, 2, 3, 4)
assertPrints(list.last(), "4")
assertPrints(list.last { it % 2 == 1 }, "3")
assertPrints(list.lastOrNull { it < 0 }, "null")
assertFails { list.last { it < 0 } }

val emptyList = emptyList<Int>()
assertPrints(emptyList.lastOrNull(), "null")
assertFails { emptyList.last() } 
   //sampleEnd
}

fun <T> Iterable<T>.lastOrNull(): T?

Returns the last element, or null if the collection is empty.

Samples

import samples.*
import kotlin.test.*
fun main() { 
   //sampleStart 
   val list = listOf(1, 2, 3, 4)
assertPrints(list.last(), "4")
assertPrints(list.last { it % 2 == 1 }, "3")
assertPrints(list.lastOrNull { it < 0 }, "null")
assertFails { list.last { it < 0 } }

val emptyList = emptyList<Int>()
assertPrints(emptyList.lastOrNull(), "null")
assertFails { emptyList.last() } 
   //sampleEnd
}

fun <T> List<T>.lastOrNull(): T?

Returns the last element, or null if the list is empty.

Samples

import samples.*
import kotlin.test.*
fun main() { 
   //sampleStart 
   val list = listOf(1, 2, 3, 4)
assertPrints(list.last(), "4")
assertPrints(list.last { it % 2 == 1 }, "3")
assertPrints(list.lastOrNull { it < 0 }, "null")
assertFails { list.last { it < 0 } }

val emptyList = emptyList<Int>()
assertPrints(emptyList.lastOrNull(), "null")
assertFails { emptyList.last() } 
   //sampleEnd
}

@ExperimentalUnsignedTypes

fun UIntArray.lastOrNull(): UInt?

@ExperimentalUnsignedTypes

fun ULongArray.lastOrNull(): ULong?

@ExperimentalUnsignedTypes

fun UByteArray.lastOrNull(): UByte?

@ExperimentalUnsignedTypes

fun UShortArray.lastOrNull(): UShort?

Returns the last element, or null if the array is empty.

Since Kotlin

1.3

Samples

import samples.*
import kotlin.test.*
fun main() { 
   //sampleStart 
   val list = listOf(1, 2, 3, 4)
assertPrints(list.last(), "4")
assertPrints(list.last { it % 2 == 1 }, "3")
assertPrints(list.lastOrNull { it < 0 }, "null")
assertFails { list.last { it < 0 } }

val emptyList = emptyList<Int>()
assertPrints(emptyList.lastOrNull(), "null")
assertFails { emptyList.last() } 
   //sampleEnd
}

@ExperimentalUnsignedTypes

inline fun UIntArray.lastOrNull(predicate: (UInt) -> Boolean): UInt?

@ExperimentalUnsignedTypes

inline fun ULongArray.lastOrNull(predicate: (ULong) -> Boolean): ULong?

@ExperimentalUnsignedTypes

inline fun UByteArray.lastOrNull(predicate: (UByte) -> Boolean): UByte?

@ExperimentalUnsignedTypes

inline fun UShortArray.lastOrNull(predicate: (UShort) -> Boolean): UShort?

Returns the last element matching the given predicate, or null if no such element was found.

Since Kotlin

1.3

Samples

import samples.*
import kotlin.test.*
fun main() { 
   //sampleStart 
   val list = listOf(1, 2, 3, 4)
assertPrints(list.last(), "4")
assertPrints(list.last { it % 2 == 1 }, "3")
assertPrints(list.lastOrNull { it < 0 }, "null")
assertFails { list.last { it < 0 } }

val emptyList = emptyList<Int>()
assertPrints(emptyList.lastOrNull(), "null")
assertFails { emptyList.last() } 
   //sampleEnd
}